I made a 16x32 led matrix on a breadboard with 8 red 8x8 matrixes. I connected the 32 columns to 4 shift registers (74HC595's) and connected the rows to 16 pnp transistors and then to two more shift registers. I have tested this setup with elcojacob's library here ( HTTP://arduino.cc/forum/index.php/topic,66988.0.html ). It works well with the example code. I wanted to try scrolling text on this setup, so I tried this code (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1267391793/7) At first this didn't work, and I tried doing what it says at the very end. Now all that results is scrolling 5x8 blocks instead of defined letters.